Vibrator



May 7,1935. C .DE 2,000,025

VIBRATOR Filed Sept. 16, 1933 jfiveni'or rfoifiv 777.1276

attorney Patented May 7, 1935 UNITED STATES PATENT I OFFICE v vniaa'ron. John McDonald Ide, Cambridge, Mass. Application September 16, 1933, Serial No. 689,784

18 Claims (Cl. 175-,-21)

The present invention relates to vibrators, and more particularly to vibrators having a low varying or substantially constant frequency with variations of temperature, and adapted to be operated magnetostrictively. Vibrators of this character are disclosed in United States Letters Patent 1,882,397, granted October 11, 1932, to George W. Pierce.

An object of the invention is to provide a new and improved vibrator of the above-described character. other objects will be explained hereinafter, it being understood that it is intended to set forth, by suitable expression in the claims, all the novelty that the invention may possess.

The invention will be explained in greater detail in connection with the accompanying drawing, the single figure of which is a diagrammatic view of a vibrator embodying the present invention and connected into a maguetostrictive oscillator.

The vibrator is shown at 2, in the form of a rod, but it may have am! other desired shape, as a tube. It is illustrated as positioned axially .0! a magnetic field, here shown as produced by coils 22 and .24. For symmetry, one of the coils is positioned on one side of the middle of the core 2 and the other on the other side. The coil 12 is connected, in series with the local battery It, between the filament or cathode 26 and the plate or anode 20, in the output or plate circuit of a vacuum tube 30. Thecoil 24 is similarly connected in the input or grid circuit of the tube, between the filament 26 and the grid or third electrode 32. The coils 22 and 24 thus form electrical paths between the filament and the plate, and between the filament and the grid respectively. The grid and the plate may, if desired, be spanned by a variable condenser 34 or the tuning condenser may be connected in parallel with one or the other oithe coils 22 and 24; or ii. the coils are suitably designed the condenser may be omitted altogether. An electric vacuum-tube oscillator is thus provided as described more fully in United States Letters Patent 1,750,124, granted March 11, 1930, to the said Pierce. As is also there stated, the local battery l8 may serve to supply the plate current, as well as to polarize the vibrator. In the illustrative drawing, polarization is effected by means 0! a separate winding 35, in series with a polarizing battery 31. A steady magnetizing or polarizing field is thus applied, over which the alternating field is superposed.

As is explained in, the said Letters Patent 1,882,397, the frequency of a particular mode 01 vibration of a rod or bar is determined by its elasticity, length and density. For some modes of vibration, the frequency is affected also by the width, thickness, radius, and the like, of the rod or bar. Different bodies have different magnetostrictive properties. Alloys containing nickel, chromium, cobalt and steel, in proper proportions, have comparatively large magnetostriction.

The present invention is the result of tests made with a large number of magnetic alloys of iron, nickel, chromium and cobalt, in varying proportions. The temperature coefficient of frequency was measured, in each case, at several points in the temperature range from 20 C. to 100 C. These researches have developed that some of the alloys have very low, substantially zero, temperature coefilcients of frequency of longitudinal vibration. It was found that the temperature coeiilcient of frequency is a function of composition, heat treatment, temperature and magnetization. Three compositions were found which gave temperature coeillcients of the order of one to fifteen cycles in a million per centigrade degree, when properly heat-treated and magnetized. These show large dynamic magnetostriction effects, so as to constitute powerful magnetostrictive vibrators, and give good frequency stabilization when used in the audio range and up to about 100,000 cycles per second with a magnetostriction, vacuum-tube oscillator, such as is disclosed in the said Letters Patent of the United States 1,750,124 and illustrated in the accompanying drawing. Alloys of such composition are useful in the form of tuning forks to serve as low, audio-frequency standards, as well as for magnetostriction oscillators, to stabilize higher frequencies.

The following considerations will help to an understanding of the present invention,

Let Zbe the length of the vibrator, I) the density 01 the material of which the vibrator is constituted, a the temperature coeillcient of linear expansion of this material, b the temperature co efllcient of Youngs modulus E, and g the temperature coeflicient of frequency of longitudinal vibration. By using well known equations for. the velocity of sound 0 in an elastic medium:

It is obvious from this equation that one way to get a small temperature coefiicient of frequency is to make alloys for which I: is opposite in sign, and nearly equal in magnitude, to a. Since a is always positive, in metals, and varies in value from l l to 12-}-l l for alloys of iron, nickel and chromium, it is desirable to make alloys for which a will be negative in sign and or this order of magnitude.

In an alloy containing 36 per cent nickel, ll to 10 per cent chromium, and the balance iron, the value of Q can be made vanishingly small, under suitable magnetic and thermal conditions. It is likewise true, as I have found, that the 2'3 per cent and 10 per cent chromium alloys are very powerful magnetostrictive vibrators. The addition oi about 13 per cent of cobalt to the iron nickel alloy containing 36 per cent nickel, reduces g to zero.

temperature coefficient or" frequency given alloy of this series, may vary with ""ture, and with the stead ir netic field to the For all these Moys, can

by heat tree. anneelin the alloys may contain alsou" anganese as deoxidizer, wil for "Ze urities should 18W, so l 31'' lo wate ials are desirable;

cobalt, clues.

measured as funct e uency is one EJKC. life Q ture,

pclczollio, write ainst '1 a polarizing so curves giving the natural frequency as a i magnetic and the t mperatwfe. these curves, mnerature ece ficients could he unoer various conditio .s of temperature 2.....cl magnetization for each specimen.

The following" were found to be favorable alloy compositions of nickel, chromium and iron: Cr 8 per cent, Ni 37 per cent; Cr per cent, lit 38 per cent; and Cr per cent, Ni 36 per cent. balance is iron, in each case.

T show the efiect of heat treatment on the variation of frequency with magnetic field, samples out from the same rod were measured in the quenched, annealed, and forged conciltions. The annealed sample showed 0.6 per cent frequency change, the forced sample 9.2 per cent change, and the quenched sample 3.1 per cent change, as magnetic field was increased to saturation. This behavior with heat treatment is typical of most of these alloys.

The tests showed that there is less frequency variation with field as the temperature rises.

The tests showed further that the addition of more than 10 per cent of chromium or of cobalt to the iron-nickel series per cent to 40 per cent nickel) reduces the dynamic magnetostriction effects.

Heat treatment is another factor which may cause marked changes in the properties of these alloys. ll. sample was annealed by heating to redness and allowing it to cool slowly in the furnace. It demonstrated that there is a crltlcal magnetizing field, for each specimen, where mpos ure coefficient changes from positive li e 1 lues, passing through zero. L e ange the temperature coeffifield varies, was shown to he healed and forged samples and very all 01 re quenched sample. By proper choice compoation, t mperature coefficients measure, or less than one l/ in a, million. per degree centlgrade, by careof magnetic field and h treatjustment, the coefliclent l ice counted upon. he less than cycles in million 12 centlgrade degree.

s research. shows while the tempera ole the o the rod may cause con use rod frequency. it thus are that "/2. -s in magnetic ileld :na Toe more n tcmrera When the equency change with go, for t annealed silos would give n a million.

tile I,

composition :Wocy variation. reuse 'lliori for one folds arger than "ted. cient varies oer. re, heat a gcss cle, arranging F are 20nd tions, to o in pram '"erature coefficient 1? any oi compositions .4 -2-, any composition the range a, oil per cent nickel 3 oer cent chmand the halance'iron in each carshould nerature coetllcient less than ten ts in a million, under suitable conditions. The desirable characteristics for frequency standards to control znagnetostrictive oscillators are, of course, excellent stabilization and small of magnetic field on frequency, in additics: to low-temperature coefllclent. The alloys alcove enumerated are all excellent ,vibrators. These alloys are practical compositions for apoiications requiring low-temperature coefficient, low magnetic-fie1d coeficient, and excellent stabilizing power, or large dynamic magnetostriction. By quenching these alloys, the magnetlc-fleld ooefilcient can be still further reduced without affecting the other desirable properties. With chromium, iron and nickel, the best 31- lion per centigrade degree.

Modifications may be made by persons skilled in the art without departing from the spirit and scope of the invention, as defined in the appended claims.

What is claimed is:

1. A vibrator having a substantially constant frequency with variations of temperature, and constituted of an alloy having about 8 to 10 parts chromium, 36 to 40 parts nickel, and the balance iron with a small addition of another substance or substances, and a coil cooperatively related to the vibrator, the relation between the coil and the vibrator being such that the current flowing through the coil is subjected to the reaction of the vibrator at a frequency which resonates with the vibrator.

2. A vibrator having a substantially constant frequency with variations of temperature, and constituted of an alloy having about 8 to 10 parts chromium, 36 to 40 parts nickel, and the balance iron with a small addition of manganese.

3. A vibrator-having a substantially constant frequency with variations of temperature, and constituted of an alloy having about 8 parts chromium, 37 parts nickel, one part manganese and the balance substantially all iron, and a coil cooperatively related to the vibrator, the relation between the coil and the vibrator being such that the current flowing through the coil is subjected to the reaction of the vibrator at a frequency which resonates with the vibrator.

4. A vibrator having a substantially constant frequency with variations of temperature, and constituted of an alloy having about 8 parts chromium, 37 parts nickel and the balance substantially all iron.

5. A vibrator having a substantially constant frequency-with variations of temperature, and constituted of an alloy having about 8 parts chromium, 38 parts nickel and the balance substantially all iron.

6. A vibrator having a substantially constant frequency with variations of temperature, and constituted of an alloy having about 10 parts chromium, 36 parts nickel, and the balance substantially all iron.

7. A vibrator having a substantially constant frequency with variations of temperature and constituted of chromium, nickel and iron, and a coil cooperatively related to the vibrator, the relation between the coil and the vibrator being such that the current flowing through the coil is subjected to the reaction of the vibrator at a frequency which resonates with the vibrator.

8. A vibrator having a substantially constant frequency with variations of temperature and constituted of chromium, nickel and iron, with a small percentage of manganese, and a coil cooperatively related to the vibrator, the relation between the coil and the vibrator being such that the current flowing through. the coil is subjected to the reaction of the vibrator at a frequency which resonates with the vibrator.

9. A vibrator having a substantially constant frequency with variations of temperature, and comprising about 8 to 10 parts chromium, 36 to 40 parts 'nickel, and the balance substantially all iron, and a coil cooperatively related to the vibrator, the relation between the coil and the vibrator being such that the current flowing through the coil is subjected to the reaction of the vibrator at a frequency which resonates with the vibrator.

10. A vibrator having a substantially constant.

frequency with variations of temperature, and comprising about 8 parts chromium, 3'7 parts nickel andthe balance substantially all iron, and a coil cooperatively related to the vibrator, the relation between the coil and the vibrator being such that the current flowing through the coil is subjected to the reaction of the vibrator at a frequency which resonates with the vibrator.

11. A vibrator having a substantially constant frequency with variations of temperature, and comprising about 8 parts chromium, 38 parts nickel and the balance substantially all iron, and a coil cooperatively related to the vibrator, the relation between the coil and the vibrator being such that the current flowing through the coil is subjected to the reaction of the vibrator at a frequency which resonates with the vibrator.

12. A vibrator having a substantially constant frequency with variations of temperature, and comprising about 10 parts chromium, 36 parts nickel, and the balance substantially all iron, and a coil cooperatively related to the vibrator, the relation between the coil and the vibrator being such that the current flowing through the coil is subjected to the reaction of the vibrator at a frequency which resonates with the vibrator.

13. A magnetic material having a substantially constant frequency with variations of temperature, and comprising about 8 to;10 parts chromium, 36 to 40 parts nickel, and the balance substantially all iron.

14..A magnetic material having a substantially constant frequency with variations of temperature, and comprising about 8 parts chromium, 37 parts nickel and the balance substantially all iron.

15. A magnetic material having a substantially constant frequency with variations of temperature, and comprising about 8 parts chromium, 38 parts nickel and the balance substantially all iron.

16. A magnetic material having a substantially constant frequency with variations of temperature, and comprising about 10 parts chromium, 36 parts nickel, and the balance substantially all iron.

JOHN MCDONALD IDE. 

